Calculate how many bags of concrete you need. Enter your project volume to get 40-lb, 60-lb, and 80-lb bag counts with cost estimates.
For small to medium concrete projects, bagged premix concrete is the most accessible and convenient option. Whether you're setting fence posts, pouring a small pad, or filling sonotubes, knowing exactly how many bags to buy saves trips to the hardware store and prevents both shortfalls and waste.
This calculator converts your project's concrete volume (in cubic feet or cubic yards) into the number of bags needed for three standard sizes: 40-lb, 60-lb, and 80-lb. Each size has a different yield per bag, and the calculator accounts for a user-configurable waste factor.
The tool also estimates cost based on typical per-bag pricing, helping you compare bag sizes and decide whether a ready-mix delivery might be more economical for your project. As a rule of thumb, if you need more than 45 bags (about 1 cubic yard), ready-mix delivery is usually faster, cheaper, and yields better quality.
This data-driven approach helps contractors minimize rework, avoid delays caused by material shortages, and deliver projects on time and within the agreed budget.
Buying the wrong number of bags wastes money and time. Too few bags mean an extra trip to the store mid-project while your mixed concrete hardens. Too many bags mean storing heavy bags that can absorb moisture and harden in the packaging. This calculator gives you exact counts with waste allowances so you buy right the first time.
Yield per bag: 40-lb = 0.30 ft³, 60-lb = 0.45 ft³, 80-lb = 0.60 ft³ Bags = Volume (ft³) × (1 + waste%) ÷ yield per bag Round up to whole bags
Result: 48 bags (80-lb)
27 cubic feet of concrete with 5% waste = 28.35 ft³. At 0.60 ft³ per 80-lb bag, you need 28.35 / 0.60 = 47.25, rounded up to 48 bags. That's about 3,840 lbs of concrete to mix. For 60-lb bags: 63 bags. For 40-lb bags: 95 bags.
The three standard bag sizes available at hardware stores are 40-lb (0.30 ft³), 60-lb (0.45 ft³), and 80-lb (0.60 ft³). Some manufacturers also offer 50-lb bags (0.375 ft³) and 90-lb bags (0.675 ft³). Always check the yield printed on the bag, as it varies slightly between manufacturers.
Bagged concrete is ideal for small projects: fence posts, mailbox bases, small pads under 1 cubic yard, and sonotube fills. Ready-mix delivery makes more sense for anything over 1 cubic yard. The crossover point depends on your local ready-mix delivery charges and minimum order requirements.
Always add water gradually — you can add more, but you can't take it out. Mix for at least 3–5 minutes until uniform in color with no dry pockets. In hot weather, wet the mixing container first and use cool water. In cold weather, store bags in a heated space before mixing.
An 80-lb bag of premix concrete yields approximately 0.60 cubic feet of mixed concrete. You need about 45 bags of 80-lb mix to make one cubic yard (27 cubic feet).
Typical retail prices (2025–2026): 40-lb bags cost $3–$4, 60-lb bags cost $4–$6, and 80-lb bags cost $5–$7. Prices vary by brand (Quikrete, Sakrete) and location. Buying by the pallet offers discounts.
Yes, when mixed properly, bagged concrete reaches the same PSI rating shown on the bag (typically 4,000 PSI for standard mix, 5,000 PSI for high-strength). The key is using the correct water-to-mix ratio.
About 45 bags of 80-lb mix, 60 bags of 60-lb mix, or 90 bags of 40-lb mix equal one cubic yard. At 80-lb per bag, that's 3,600 pounds to mix for a single cubic yard.
Yes, a standard contractor's wheelbarrow holds about 6 cubic feet, enough for two 80-lb bags. Mix with a hoe or square shovel. For more than 10 bags, rent a portable concrete mixer for much faster results.
Standard bags set in 20–40 minutes and can support weight in 24–48 hours. Quick-setting bags set in 10–15 minutes. Full cure takes 28 days. Keep the surface moist for best strength development.
Ready-mix is preferred for any pour over 1 cubic yard, for structural work requiring consistent quality, or when speed is essential. The break-even point is typically around 1–1.5 cubic yards where ready-mix becomes cheaper than bags.
Most 80-lb bags require about 3 quarts (0.75 gallons) of water. Always check the bag label. The mix should be workable but not soupy — like thick oatmeal. Too much water weakens the concrete.